Infrared Thermal Imaging And Optical Lock-in Thermal Imaging For Non-destructive Testing Applications

Infrared thermal wave imaging is widely used in NDT(nondestructive testing) in 1990s in America.At present mainly two different procedures of active thermography are being used: Pulse and Lock-in Thermography.With pulse thermography,the examined material is warmed up with a short energy pulse(light, eddy current,or ultrasonic pulse) and the heat response is recorded after a certain time.The result is an infrared image which indicates material defects in different depths.Since pulsed thermography has its limitation in detecting faint fatigue,stress concentration and large scale testing.When using pulsed thermography,local variations of illumination and surface emissivity should also be strictly required.All these factors limit the application of pulsed thermography,so we introduce lock-in thermography which can solve all these difficulties mentioned above.The carbon fiber reinforced plastic(CFRP) is an innovative material.In order to repair the board we need to know information about it after being damaged.Compared the results of impact damage CFRP board which has been damaged by different magnitudes of force IR thermography has been applied to test the carbon fiber reinforced plastic...